Improved slide-valve for steam-engines



PATENT rrrcn.

J. VAUGHAN MERRICK, OF PHILADELPHIA, PENNSYLVANIA.r

IMPRDOVED SLIDE-VALVE FOR STEAM-ENGINES.

Specication forming part 0f Letters Patent No. 34,57, dated February 25, 1862.

To all whom t may concern:

Be it known that I, J. VAUGHAN of Philadelphia, Pennsylvania, have invented an Improvement in Slide-Valves for Steam- Engines; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings and to the letters of reference marked thereon.

My invention consists of a slide-valve and balancing-plate in combination with a doubleported cylinder-face, the valve being provided with such openings and the balancing-plate with such chambers and ports as to permit the steam to pass to and from the cylinder in the manner described hereinafter. The object of this combination has been to obtain all the important advantages alluded to hereinafter as being derived from a properly-balanced slide-valve and from one having a short stroke.

In order to enable others familiar with the construction of steam-engines to make and use my invention, I will now proceedto describe its construction and operation.

On reference to the accompanying drawings, which form a part of this specification, Figure 1 is a vertical section of the steamchest and part of the cylinder of a steam-engine with my improved slide-valve and balancing-plate; Fig. 2, a transverse section on the line l 2, Fig. l; and Fig. 3, an inverted plan view of the equilibrium or balancing plate.

Similar letters refer to similar parts throughoutthe severalviews.

A and A represent the opposite ends, and B the detachable cover, of the steam-chest, which is secured to or forms a part of the cylinder c.

D and D are the opposite steam-passages, and E the exhaust-passage, each steam-passage being divided into two ports a and a at the face against which bears the valve F. Directly through this valve pass the two openings d and d', each of which is of the same length and of the same or nearly the same width as one of the steam-ports. A central opening c, situated midway between the two openings d and d', also passes directly through the valve, the latter being provided with spin- MERRIOK, l

dles G G', which, as usual, pass through stufting-boXes formed on thesteam-chest.

' Above the valve F and bearing on the upper surface of the same is the equilibrium or balancing plate H, which is provided at the opposite ends with projections t' t', the latter bearing against the ends of the steam-chest, and thus serving to maintain the plate in its proper longitudinal position, while the sides of the steam-chest prevent it from moving laterally. On each side of the balancing-plate is a longitudinal rib m, the lower edge of which coincides with the under face of the valve F, both resting on the faces@ of the cylinder, and the two ribs of the plate serving as guides to maintain the valve in its proper lateral position during its movement.

Within the balancing-plate are formed the two chambers I and I', and midway between the latter a central chamber J, the two former chambers terminating at the under face of the plate in the two ports n and n', and the chamber J, having an opening n2 directly opposite to and of the same or nearly the same dimensions as the exhaust-port q in the face of the cylinder, the ports n and n of the plate being also directly opposite to and of the same or nearly the same dimensions as the ports a and a of the cylinder.

Set-screws passing through the cover B of the steam-chest and springs may be used to maintain the under face of the balancingplate in close contact with the valve, and the under face of the latter, as well as the ribs fm. m, of the plate, in close contact with the face 0c of the cylinder, thereby preventing that jumping of the valve and plate to which during the movement of the engine they would be liable, but for these or other equivalent preventative appliances.

In Fig. l the valve F is illustrated as having reached the limit of its movement in the direction of the arrow, this position of the valve permitting the steam to pass from the steam-chest into the passage D in two currents, one directly through the port a and the other current through the port n of the balancing-plate into the chamber I and thence through the port n', directly through thel opening d of the valve, and through the port a. In the meantime the exhaust-steam at the opposite end of the cylinderis making its Wayin two currents from the passage D to the exhaust-passage E, one current taking a comparatively direct course through the port a into the central opening e of the valve F, and thence through the port q into the eX- haust-opening, While the other current takes a more ci rcuitous course through the port d, through the opening d of the valve, through the port n, chamber I', and port n of the balancing-plate, and thence through the central opening e of the valve, and through the port q to the exhaust-passage of the cylinder.

It will be evident that when the valve has reached the limit of its movement in the direction contrary to that pointed out by the arrov7 the direction of currents of steam to and from the cylinder Will be reversed, and that the ports and chambers in the balanceplate serve alternately to direct the steam to and from the cylinder according to the posisire to claim, broadly, the double-ported slidevalve and the balancing or equilibrium plate tion of the valve.

,It will also be evident to those familiar with the construction of vsteam-enginesthat the plate H, situated as it is in close steamtight contact with the valve and prevented by its ribs m and m from bearing with more force than necessary on the valve, must serve to relieve the latter from that excessive and undue pressure of steam to which ordinary valves are subjected, while leakage is entirely prevented.

Double steam-ports have been heretofore used in steam-engines for the purpose of presenting an extended area of opening for the passage of steam to and from the cylinder by a very short movement of the valve, the eccentric and other appliances for operatin g the valve being consequently reduced in size, and a general diminution of friction and Wear and tear of parts effected.

Different kinds of balanceing or equilibri um plates have also been used in connection with slide-valves for the purpose of relieving the latter from that excessive friction which detracts so seriously from the power of` an engine furnished with ordinary unbalanced slide-valves, and for the purpose of rendering the appliances for operating the valve lighter,

more simple, and inexpensive, and at the same time veasily controlled by the attendant engineers.

All the advantages resulting from the -use of a double-ported slide-valve with a short stroke anda balance-plate are `so, fully attained by my above-described improvements that the latter are especially applicable to large marine engines, those of the United States gunboat Miami affording a practical proof not only of the easy Working of the valve itself, but of the simplicityand inexpensive character of the valve-gearing, and the facility with which the valve and consequently the engines can be controlled by the engineer, compared with the exertion clemanded in the management of ordinary slidevalves of large engines, by the aid of much heavier and more costly appliances than those f required for controlling my improved valves.

I Wish it to be understood that Ido not de# viewed separately, nor do I claim the peculiar form ot' balancing-plate With its ribs m, as

represented, such a plate having been heretofore used in England; nor in claiming the combination do I desire to restrict myselfto the precise form or construction of the balancing-plate or slide-valve, as both may be modified Without departing from'the main feature of my invention; but

I claim as my invention and desire to secure by Letters Patent- Y A slide-valve and balancing-plate, in combination with a double-ported cylinder-face, when the said valve is provided with such openings, and the said balancing-plate with such chambers and ports as to permit the,

steam to pass to and from the cylinder, substantially in the manner herein set forth.

In testimony whereof I have signed my name to this specification in the two subscribing Witnesses.

J. VAUGHAN MERRICK. Witnesses:

HENRY HoWsoN, JOHN WHITE.

presence of i 

